General > General Technical Chat
The "All American Five", & more dangers!!
GlennSprigg:
(Please don't move this. It's mainly about 'general' topics).. :)
The "All American Five" refers to the mass produced valve radios, by very many manufacturers, from the 1930's. Apart from the standard 5 tubes & their functionality, their emphasis was on 'cheapness' of manufacture. There is/was NO power transformer, and relied on the American line voltage of 110/120-v to directly feed Plates (partly via resistors), and series connected tube 'heaters' of higher Filament Voltages etc., so that no mains transformer is/was needed. OK, I get it, but half the time, one ended up with a 'Live' Chassis for the uninitiated!? :P
So many times, I've seen ccts where a 'power' switch, if any, actually switches the Neutral! The VAST majority of power plugs I've seen in America have only 2 pins, and no 'Earth' pin. Now I know that most 'modern' plugs/sockets there now are 'polarized' by way of a slightly wider pin, but still with no Earth?? I understand too that this is 'just' 110v, not 240v like in Australia, but I don't understand the attitude. I see numerous Youtube videos where people in the U.S. plug equipment into un-switched outlets on their bench. Ok, YOU might have wired it correctly. :(
In Australia, we MUST have an Earth too, unless the device/machine is 'Double-Insulated', like a certain hair dryer etc. It just seems that America is more blase' about Neutrals & Earthing ?? (And yes, I understand about isolation transformers & isolated Variacs etc.) :phew:
joeqsmith:
This old Crosley 718 belonged to my wife's grandparents. A couple more tubes and it uses a transformer.
https://www.eevblog.com/forum/repair/old-console-radio-repair/msg1455644/#msg1455644
I posted once a section from the ARRL handbook on safety. They talk about the dangers of 110, mainly because people feel working with it is low risk and get comfortable around it.
Tom45:
Yes, everything you described is accurate. In addition, no outlets back then had grounds nor were they polarized.
The All American Five radios were designed to be extremely low cost. The enclosures and knobs were plastic so in normal use there was no chance that a user would be exposed to a possibly hot chassis.
You are getting alarmed over practices from well over a half century ago.
Automobile seat belts and child car seats didn't exist either. I was born in 1945 and nobody thought twice about having their children free to roam around in the back seat while driving. Today parents would be in big trouble if they did that.
Somehow most of us managed to survive radios with hot chassis and cars with no seat belts or child seats.
Were people tougher back then? Are people a bunch of wimps now? I'll leave that to others to decide.
16bitanalogue:
--- Quote from: Tom45 on April 27, 2020, 02:05:45 pm ---
Were people tougher back then? Are people a bunch of wimps now? I'll leave that to others to decide.
--- End quote ---
Neither. It has more to do with safety, policy, and the squeaky wheel. "Unsafe At Any Speed" is what sparked the safety revolution in the automobile industry in the US.
Are manufacturers responsible to ensure that their products can be used safely (seat belt) even though the individual may not use that mechanism (seat belt). Let's have some real talk. People will be stupid and cause accidents, so additional safety mechanisms are, I would argue, value added.
When do they become intrusive and/or political is the question IMO. See mandatory back up camera because Mom ran over her daughter while backing up. Tragic. Truly. But a necessity?
rstofer:
--- Quote from: GlennSprigg on April 27, 2020, 01:16:40 pm ---So many times, I've seen ccts where a 'power' switch, if any, actually switches the Neutral! The VAST majority of power plugs I've seen in America have only 2 pins, and no 'Earth' pin. Now I know that most 'modern' plugs/sockets there now are 'polarized' by way of a slightly wider pin, but still with no Earth?? I understand too that this is 'just' 110v, not 240v like in Australia, but I don't understand the attitude. I see numerous Youtube videos where people in the U.S. plug equipment into un-switched outlets on their bench. Ok, YOU might have wired it correctly. :(
--- End quote ---
You must have been living in some pretty old housing because U-ground receptacles have been required since 1951 for the laundry and eventually covered the entire house by 1962. Polarized receptacles have been available since the 1880s but not mandatory until 1962 when the NEC required receptacles to be both polarized and grounding but they were in common use much earlier.
I use power outlet strips on my bench and most have switches. I have never used the switching feature but it does exist. There are a number of GFCI device configurations and I suppose a receptacle style could be used on a bench.
Today we have a requirement for arc-fault breakers serving certain areas of the residence and GFCI protected outlets in many others.
Lowe's still carries 2 wire unpolarized plugs. I saw some on the shelf the other day when I was looking a 2 wire polarized plug which they didn't have. There are a lot of two-wire applications including table lamps, toasters, hair dryers and carving knives. Mostly, it works out fine.
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